The purpose of this contract is to support development and maintenance of the Hazardous Substances Data Bank (HSDB), which contains more than 5000 records on chemical substances. HSDB is a toxicology data file on the National Library of Medicine's (NLM) Toxicology Data Network (TOXNET[unreadable]). It focuses on the toxicology of potentially hazardous chemicals. It is enhanced with information on human exposure, industrial hygiene, emergency handling procedures, environmental fate, regulatory requirements, nanomaterials, and related areas. All data are referenced and derived from a core set of books, government documents, technical reports and selected primary journal literature.